Railway traffic controlling apparatus



March 2, 1943- .1. J. VANHORN RAILWAY TRAFFIC CONTROLLING' APPARATUSFiled July 1o, 1941 '2 sheets-sheet 1 @www E@ WMIMI INVENTOR JaImsuS7 JVllhorn HIS A'rToRNEY March 2, 1943. J. J. VANHORN 2,312,740'

RAILWAY TRAFFIC CONTROLIJNG APPARATUS I Filed July 1o, 1941 2sheets-sheet 2" Patented Mar. 2, 1943 RAILWAY TRAFFIC CONTROLLINGAPPARATUS J ames J. Vanhorn, Pittsburgh, Pa., assigner to The UnionSwitch & Signal Company, Swissvale, Pa., a corporation of PennsylvaniaApplication July l0, 1941, Serial No. 401,757

(ci. 24e- 26) l Claims.

` My invention relates to railway trafc conjtrolling apparatus, and moreparticularly to apparatus for control of track indicators.

The o'ice of a remote control system for a railway is usually providedwith a track model of the stretch of track associated with such controlsystem, and track indicators in the form of small electric lamps areplaced on such track model one for each of certain designated tracksections of the stretch. Each such lamp is illuminated through themedium of the control system when the respective track section isoccupied in order that the operator may know the location of the trainsoperating over the stretch. Wayside signals associated with trackswitches of passing sidings when governed by such remote control systemare usually provided with approach locking which is controlled in partby approach relays, each of which relays is controlled by the trackrelay of one or more track sections in the approach to the respectivesignal. It is customary to use the approach relays as means forcontrolling track indicators, each such approach relay when deencrgizedin response to a train occupying the respective track section orsections, causing the remote control system to transmit an indicationinfluence to the remote oice where it results in a respective indicationrelay being energized and picked up to complete a circuit for the trackmodel indicator lamp that corresponds to the same track section orsections. In this manner the operator is informed when a train isapproaching a signal at which the operator can hold the train by settingthe signal at stop or can advance the train by clearing the signal. Whenthe remote control system is a centralized traffic control system of thetime code type, the number of track occupied indication codes that canbe provided without increas-` ing the usual coding units and otherapparatus is limited.' In such centralized trafuc control system forsingle track railroads it is desirable to provide track occupiedindications for the track section or sections between adjacent passingsidings and for the track section or sections between the two ends of asiding.

In view of the above discussed circumstances in railway signalingsystems, a feature of my invention is the provision of railway trailiccontrolling apparatus incorporating novel means for providing trackoccupied indications in centralized traine control systems forrailroads.

y Another feature of my invention is the provision in centralizedtrafiic control systems for single track railroads of novel means forindieating at the voffice occupancy of the track stretch between theadjacent entering signals of adja-` cent sidings, and occupancy of thetrack stretch between the leaving signals at the two ends of a siding.

Again, a feature of my inventionis the provision of novel and improvedmeans for remote control systems for railways wherewith the occupancy ofthe stretch of track between adjacent sidings or ,between the two endsofa siding is indicated by the present equipment andvadditional repeaterrelays controlled over line circuits requiring line wires are avoided.

The above features of my invention, as Well as other advantages whichwill become apparent from the following specification, are attained bycontrolling a track indicator corresponding to the stretch of trackvbetween adjacent passing sidings, or corresponding to the stretch oftrack between the two ends of a siding, over a circuit which includes inAseries a front contact of eachY of two indication relays, one governedby each of the two approach relays associated with signals of vsuchstretchof track. Inthe case of a stretch betweenadjacentsidings, theapproach relay of each of the two adjacent entering signals associatedwith such sidings is controlled over the track relay of each tracksection intermediate such entering signals as well as over the trackrelays of other sections in the approach to the respective signal. Eachapproach relay when deenergized due to a train approaching therespective signal causes an indication code to be transmitted to theoffice where a corresponding indication relay is energized and pickedup.

Since under such arrangement the only traffic condition under which thetwo approach relays of the two adjacent entering signals for adjacentsidings are deenergized at the same time is when the stretch of trackbetween such signals is occu-l pied, the indicator controlled over acircuit in cluding a front contact of each of the two respectiveindication relays indicates a track occupied condition for this stretchof track only. I provide a directional stick relay for each approachrelay for by-passing the control of the approach relay around thecontact of the track relay of the usual detector track section fortrains moving in the direction opposite to that governed `by theassotion relaysgoverned by the two approach relays of the two leavingsignals of such siding. Again,

since the only condition in which the two approach relays are releasedat the same time is when a train occupies the stretch between the twoleaving signals, such indicator is displayed only in response tooccupancy of this stretch between the two ends of the siding.

I shall describe two forms of apparatus embodying my invention, andshall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a diagrammatic view showing oneform of apparatus embodying my invention when used to indicate occupancyof a stretch of track between two ladjacent sidings of a single trackrailway, and Fig. 2 is a diagrammatic view showing one form of apparatusembodying my invention when .used to indicate occupancy of a stretch oftrack between the two ends of a passing siding of a single trackrailway. In each of the two views like reference characters are used todesignate similar parts.

Referring to Fig. 1, the reference character .F designates a stretchofsingle track railway which is lprovided with track switches 5S and 1Sleading to sidings Fa and Fb. I'hat is, track switches 5S and 'IS arethe adjacent switches of sidings Fa and Fb.

This stretch of track F is divided by the usual insulated rail joints`into track sections 6T, 5T, AST, 1T and 8T; the track sections 5T and 1Tbeing detector track sections at switches 5S and 1S, respectively. Eachsuch track sections is provided with a track circuit comprising abattery 2 connected across the rails. at one end of the section, andatrack relay .designated by the reference character R plus a preiixcorresponding to the associated section connected across .the rails atthe other end of thefsection.

Each track switch 5S and 'IS is provided with the usual protectingsignals, switch 5S being associated with entering signal LS andleavingsignals R6 and RCS, and switch 'IS being associated with entering signalR8 and leaving signals L8 and LCB. These signals may be of any standard.type and are shown by the usual conventional symbols, it being observedthat entering signals L6 and R8 and leaving signals R6 and L3 comprisetwo signal mechanisms mounted on a single mast. Only certain of thecontrol and voperating circuits for these signals` of Fig. 1 are shownfor the Vsake of simplicity since such circuits form no part of myinvention and all of them are not required for a full understanding ofthe invention. Itis sufficient for this application to point out thatthese signals associated with the track switches are controlled in partby a centralized traic control system to be described hereinafter andwould also be .controlled by trailic conditions of the stretch. It is tobe noted that although the stretch of .track between entering signals L6and R8 is shown as consisting of but one track section AST and nointermediate signals are provided it is to be understood that thisportion of track may be formed into a plurality of track sections andintermediate signals may be located at selected points if desired. Inthe arrangement here shown, leaving signal LAS serves as an approachsignal for entering signal L6 and leaving signal RAS serves as an`approach signal for entering signal R8.

It should -be pointed out at thisv time that in order to simplify thedrawings, certain contacts of the several ,relays are shown remote fromthe relay winding and certain contacts of other .devices are shownremote from the device. In each such instance the contact is identifiedby the reference character for the relay or device ybeing locatedadjacent thereto and by the contact being shown in the positioncorresponding to the normal position of the relay or device.

The signal R8 is provided with an approach over front contacts l0, iland l2 of track relays `STR, ETR and ASTR, respectively, winding ofrelay RBAR, front contacts I3, I4 and i5 of relays ASTR, 5TR and ETR,respectively, and to terminal C of the same source of current. Thusapproach relay RSAR associated with entering signal R3 at siding lFb iscontrolled by the track relay of detector track section 5T at the nextadjacent passing siding Fa and by the track relay of section 'BT in theapproach to the leaving signal R6 at siding Fa as well as by the trackrelay of intermediate section AET. In order to provide proper control ofapproach vrelay RSAR under the various traic conditions atvswitch 5S,contacts l0 and i5 of track relay GTR lvare by-passed by contacts I8 and19, respectively, closed when signal RAS is set at stop. Furthermore,front contacts l1 and 20 of a directional relay LGS to lbe referred tolater, and front contacts i3 and 2! of a relay SRWP also to be referredto later com- .plete shunt paths for ley-passing the circuit ofapproachrelay RBAR around the control of track relays -BTR and BI'R aswill be understood by an inspection .of Fig. 1. It is to be seentherefore that approach relay RSAR is energized and picked up when tracksections 6T, 5T and ABT in the approach to signal R8 are unoccupied;when scftions 6T and AST are unoccupied and section 5T is occupied .ifdirectional stick relay LSS is picked up closing front contacts Il and2B; when sec tions 5T and AET are unoccupied and section EST is occupiedproviding signal L5 is set at stop closing contacts i6 and l 9, and alsowhen section AST is unoccupied and relay SRWP is picked up closing frontcontacts I8 and 2l, irrespective oi the traic condition of sections 6Tand 5T.

Approach relay LBAR is included in a normal circuit that passes fromterminal B over front contacts 24, 25 and 26 of track relays BTR, TTR

and ASTR., respectively, winding of relay LAR, front contacts 21, 28 and29 of relays AETR, ITB, and BTR, respectively, and to terminal C. Thusapproach relay LSAR associated with entering signal L6 at siding Fa iscontrolled by the track relay of the detector track section 1T at theadjacent siding Fb and the relay of section 8T in the approach to theleaving signal L8 at siding Fb as well as by the track relay ofintermediate section AST. In order to provide proper control of approachrelay LSAR ifor the different traiilc conditions at switch ,'IS, frontcontacts 25 and 29 of track relay 8TH. are by-passed by contacts 3S and33, respectively, which are closed when signal LA8 is set at stop; frontcontacts 25 and 28 of track relay [TR are by-passed by front contacts 3|and 34, respectively, of a directional stick ref lay RBS, to be shortlydescribed; and contacts of both track relays 8TR and 'ITR are by-passedby shunt paths including front contacts 32 and 35 of a relay IRWR alsoto be shortly described. Consequently, approach control relay I iJAR isenergized and 4picked up when sections 8T, 7T and AST in the approach tosignal L3 are unoccupied; when sections 8T and AT are unoccupied andsection TT is occupied, providing directional relay RSS is picked upclosing front contacts y3l and S; when sections ABT and 1T areunoccupied and section 8T is occupied providing signal LAB is set atstop closing contacts 30 and 33; and when section AST is unoccupied, andrelay 'ERWP is picked up closing front contacts 32 and 35.

From the foregoing description of the control of approach relays RSARand LSAR it is to be observed that the only time these tWo relays arereleased at the same time is when section AT is occupied. That is tosay, the only time when these two aproach control relays are bothreleased is under the condition that the track section between the twoentering signals L6 and R8 is occupied.

As stated hereinbefore, a centralizd traino control or remote controlsystem is associated with th stretch of track F for controlling theswitches S and 'ES and the signals associated therewith. Suchcentralized traiiic control system may take dilerent forms and may be,for example, that, covered by Letters Patent of the United States No.2,229,249, granted January 2l, 1941, to L. V. Lewis for Remote controlsystems. In the present application only that portion of the apparatusof such centralized trafc controlling system necessary for a completeunderstanding of my invention has been shown. An oiiice FS is connectedto stations l--S and .Fiby a line circuit designated C. T. C. linecircuit. Coding units which are indicated conventionally as CSO, CS? andCS-5 are provided at the oice FS and stations 1-8 and 5 6, respectively.As set forth fully in the aforementioned Lewis Patent No. 2,229,249, theoperator at the oilce FS can through the medium of the coding unitstransmit a control code to either station 5--6 or lfor selectivelyenergizing control relays which govern the positions of the track switch5S or 'iS the case may be, or which govern the positions of the signalsassociated with these track switches. At station 5 5 only the controlrelays ERWP and LSSR are' shown since the other control relays locatedat 'this station are not involved in my present invention. Relay SRWPwhen picked up 1s eiective to cause operation of track switch 5S to itsreverse position, that is, to the position for traic to move to and fromsiding Fa, operation oi the switch being accomplished by the usual powerswitch machine governed over a circuit controlled by relay SRWP. Thepoint to be noted in connection with relay 5RWP asfar as the presentapplication is concerned is the fact that front contacts i3 and 2! ofthat relay are in eluded in the circuit network for approach reiay RAR,so that relay 5RWP when picked up to cause switch 5S to be set formovement to the siding, by-passes the control circuit or" relay REARaround track relays STR and STR and approach relay RSAR is released onlyat such time that track section A5T is occupied. It is to he noted thatin place of using contacts I8 and 2i ci switch control relay SRWP forby-passing the circuit of approach control relay RSAR around trackrelays 5TR and STR, contacts it and 2i may be contacts of the usualswitch repeater relay governed by the position of switch 5S.

Control relay LiiSR at station 5-5 when picked up in response to acontrol code completes a circuil:l for a signal control relay LAl-I,such circuit including terminal B, front contact 3S ofrelay LSR. contact39 operated by switch v5S and closed when the switch is set at itsnormal position, winding of relay LSAH, front contact 'iii voi trackrelay ETR and terminal C. Relay LtA-I- when picked up closing frontcontact M completes an obvious operating circuit for signal LAS tooperate that signal 'to a proceed position. In accordance with myinvention relay LSAH also controls directional stick relay LGS, thepickup circuit for relay LSS extending from terminal B over back contacti3 of track relay 5'IR, front contact d2 of relay LSAI-I, winding ofrelay LGS and to terminal C. Relay LBS when picked up closing its ownfront contact 4d completes a stick circuit path around contact 42 of thesignal control relay LGAH. It is to be recalled that front contacts iland E@ oi relay LiiS are interposed in the circuit network of approachrelay RSAR. The function of directional stick relay LBS will appear whenthe operation of the apparatus of Fig. 1 is described.

At station 'i-B only the switch control relay 'HRWP for governingoper-ation of switch IS to its reverse position, and the signal controlrelay RHSR for signal R3 are shown since the other control relays ofthis station are not involved in the present invention. Relay 'IRWP whenpicked up in response to a proper control code transmitted from the omcein addition to causing operation of switch 'ES to its reverse positionthrough the medium of the usual switch machine not shown, also controlsat its front contacts 32 and 35 by-pass circuits in the circuit networkfor approach relay LAR, as described hereinbefore. Again', it is to benoted that in place of using contacts 32 and 35 of switch control relay'iRWP to by-pass the circuit of approach relay LSAR around contacts oftrack relay ETR and BTR, contacts 32 and 35 may be contacts of the usualswitch repeater relay governed by the position of switch 1S. Relay RBSRis picked up in response to a control code transmitted from the oiiiceand completes at its front contact l5 a circuit ior a signal controlrelay RSAH, such circuit also including contact 46 closed when switch'."S is set at its normal position and froritcontact 41 of track relayTTR. Signal control relay RSA1-I when picked up closing front contact48, completes an obvious operating circuit for signal RA8 and thissignal is operated to a proceed position. In accordance with myinvention, signal control relay RBAH controls directional stick relayRBS, the pick-up circuit for relay RBS including terminal B, backContact 49 of track relay llTR, front contact 5B of relay RSAH, windingof relay RSS and terminal C. Relay RBS when picked up to close its ownfront contact 5I, completes a stick circuit path around front contact5!) of the relay RBAH. It is to be recalled that front contacts 3| and313 of the directional stick relay R8S are interposed in the circuitnetwork for the approach relay'LAR and the function of directional relayRSS will also appear when the operation of the apparatus of Fig. 1 isdescribed.

At the office FS indication relays LEAK andv R8AK and an indication lamp5E have to do with the present invention. The lamp 5E is preferably on atrack model of the stretch F to indicate when illuminated occupancy oftrack section AST, that is, to indicate the presence of va train betweenthe entering signals L and R8 of the adjacent sidings Fa and Fb.Indication relay LSAK is effectively energized and picked up by means ofthe centralized traliic control system in response to a preselectedindication code transmitted from station 5 5, and Vwhich indicationIcode is initiated when approach relay LGAR is released closing backcontact 52 to apply positive volta-ge to a designated terminal of thecoding unit CSS of station 5 6. Likewise, indication relay RBAK 'iseffectively energized and picked up in response to a preselectedindication code transmitted from station 1 8, and which indication codeis initiated when Iapproach relay RBAR is released closing back contact53 to apply positive voltage to a designated terminal of the coding unitCS1 of station 1 8. Relays LBAK and RSAK when picked up complete acircuit for lamp SE, such circuit including iront contact 54 of relayLSAK in series with `front contact 5S of relay RBAK as Will be apparentby an inspection of Fig. 1.

In describing the operation of the apparatus of Fig. 1 it is wto benoted that normally, that is, when the stretch of track F is unoccupied,the track relays are all picked up, and approach relays LSAR and RBARare energized with the result that indication relays LSAK and RB'AK atthe oice FS are released and vlamp 5E is dark. In the event signal RAEis operated to a proceed position to permit an eastbound train to movethrough the stretch of track F and such eastbound train enters section6T, approach relay RSAR is released when track relay STR is shunted, andrelease of approach relay R8AR causes an indication code to betransmitted from station 5 3 which results in the indication relay RBAKat the office being energized and picked up. It is to be observed thatapproach relay RSAR in being released would also control the usualapproach locking for signal R8. The eastbound train on advancing intodetector section 5T shunts track relay STR to open additional points inthe control circuit for approach relay RBAR. This eastbound train uponentering section AST to shunt track relay ASTR opens the Vcircuit. lforapproach relay RAR 4at additional points and also opens the circuit forapproach relay LSAR associated with the westbound entering signal L6.The release of approach relay LSAR causes an indication code to betransmitted from station y5 5 which results in indication relay LSAKbeing picked up. Since beth indication relays RSAK and LSAK are nowenergized and picked up, the lamp SE is illuminated -to indicate thatthe section AST is Voccupied by this eastbound train. To advance thisleastbound train beyond siding Fb, the operator transmits a control codefor picking up the relay RSSB. at station 1 8 so that signal vcontrolrelay RBAH is picked up and the signal RAS is operated to a proceedposition. The eastbound train upon moving past signal R8 to entersection 1T shunts track relay 'ITR causing signal vcontrol relay RBAH tobe deenergized and released and signal RA8 to be restored to its stopposition. Signal control relay R8AH is slow releasing in character andYhence when track relay HTR is shunted clos-ing its back contact 49 thepick-up circuit of directional stick relay RBS is closed during the slowrelease period of relay R-BAH, and relay RBS when thus picked up isretained picked up subsequent to the release of relay RSA1-I over itsstick circu-it with the result that direction-al relay RBS remainspicked up until such time as the eastbound train vacates track section'IT and track relay TTR is picked up. Since for eastbound traffic, thewestbound signal LAS is set at stop closing contacts 30 `and 33 andsince directional vstick relay RSS is Picked up closing front contacts3| 4and 34, the circuit network for approach relay LGAR is closed aroundthe control ci track relays TTR and STR with the result that approachrelay LSAR is revacates track section AST. The approach relay RBAR isalso picked up when the train vacates track section AST unless a secondor following eastbound train happens to be occupying the section 6T orthe section ST. It is to be seen therefore that under normal movement ofeastbound traiic both approach relays RBAR and LSAR are reenergized whenthe eastbound train vacates section AST and both indication relays RBAKand LSAK are released causing lamp SE to become dark. Furthermore, inthe event a second eastbound train occupies section 6T causing approachrelay R8AR to remain released and its corresponding indication relay RAKto remain energized, subsequent to the first eastbound train vacatingsection AST, the other approach relay LBAR is reenergized and picked upcausing indication relay LSAK to be deenergized with the result thatlamp SE becomes dark indicating that the track section AST between thetwo sidings is unoccupied. In other words, indication lamp SE whenilluminated informs the operator that the track between the enteringsignals R8 and L5 is occupied.

The operation of the apparatus of' Fig. 1 for a westbound train issimilar to that just described in connection with an eastbound train,and it is believed that the operation of the apparatus for westboundtraino will be apparent from an inspection of Fig. l when considered inconnection with the description of the operation of the apparatus foreastbound traflic.

It should be pointed out that the released position of directional relayRSS associated with eastbound traic is checked by the fact that its backcontact '5S is interposed in the control of the westbound signals LABand LCS, and that the released position of directional relay LBSassociated With westbound traic is checked by its back contact 51 beinginterposed in the control of eastbound signals RAS and RCS.

Referring to Fig. 2, a stretch of single track Fl includes both ends ofpassing siding Fa, such siding being provided with track switches 5S and3S. This stretch FI is formed into track sections AZT, 3T, AT, Aar, e'r,5T and At'r; and each of which track sections is provided with a trackcircuit including a battery 2 connected across the rails at one end ofthe section and a track relay R plus a prex corresponding to the sectionconnected across the rails at the other end of the section. Trac atswitch 5S is governed by entering signal LB and leaving signals R6 andRCS, and at switch 3S by entering signal R4 and leaving signals L4 andL04. It is to be noted that there are three track sections 4T, A4T and6T between leaving signals R6 and L4. These signals of Fig. 2, like thesignals of Fig. 1, would be controlled in part by traic conditions ofthe associated stretch and in part by a centralized traiic controlsystem. Of such control for the signals of Fig. 2, only that portionthat has to do with the present application is shown. In Fig. 2 anapproach relay RSAR associated with signal RS is normally energized by acircuit formed from terminal B over front contacts 58, S9, 6D, 6| and 62of track relays AZTR, 3TR, 4TR., A4TR and STR, respectively, winding ofrelay RGAR, front contacts 63, E4, SS, 66 and 61 of track relays STR,A4TR, 4TR, STR and AZTR, respectively, and to terminal C. In the circuitfor approach relay REAR contacts 68 and 69 closed when Signal R4 is setat stop, by-pass front contacts S8 and 61, respectively, of trackenergized and picked up as soon as the train 754 relay AZTR, and thefront contacts lo and 1| of a switch control relay-3RWP to be referredto later, form a shunt path around the contacts of both track relaysAZTR and 3TR.

An approach control relay LliAR for signal LA-l is provided with anormal circuit including and 85 of switch control relay SRWP form shuntpaths around the contacts of both track relays STR and ASTR.

In the associated centralized traic control system, the cnice FS isconnected to stations 6 and 3 6 over the C. T. C. line circuit, andcoding units CSO, CSS and C53 of oflice FS and stations 5 5 and 3 4,respectively, are associated with such line circuit in the same manneras explained in connection with Fig. 1 and as fully explained in PatentNo. 2,229,249, reierred to hereinbefo-re. At station 5 6, only the onecontrol relay ERWP is shown since that is the only control relayinvolved in the apparatus oi Fig. 2 and this relay is effectivelyenergized and picked up in response to a control code transmitted fromthe oiiice and relay 5RWP 'when picked up is effective to set in motionthe i operation of moving switch 5S to its reverse position the same asin Fig. 1. The point to be noted inconnection with control relay SRWP inFig. 2 is the fact that when this relay is picked up closing frontcontacts 84 and 85, `by-pass paths vare formed for the circuit ofapproach relay LLlAR around the contacts of track relays STR :and ABTR.At stations 3 4, only the one oontrol relay SRWP is shown Since this isthe only control relay at that station involved in the presentapplication. Relay BRWP is picked up in response to a proper controlcode transmitted from the office and whenpicked up it is effective tocause operation of switch 3S to its reverse position and to complete atits front contacts and 'il by-pass paths around the contacts of trackrelays ETR and A2TR for the circuit of approach control relay REAR. Itshould again be pointed out that in place of contacts of the switchcontrol relays 3RWP and 5RWP being used in the networks of theassociated approach relays, contacts of the usual switch repeater relaysgoverned by the positions of switches 3S and 5S can be used in thenetworks since a switch repeater relay indirectly repeats the positionof the switch control relay.

` At the oce an indication relay LAAK is energized in response to anindication code sent out from station 3 4 due to approach relay MARlbe'ing released to close back contact 86 and applying positive voltageto a designated terminal of the coding unit CSS. Indication relay REAKat the ofdce is energized in response to an indication code sent fromstation 5 5 when approach relay RGAR is released to close backconoccupies detector section 5T, a directional stick the track relaysare allpicked up and approach relays RSAR and LliAR are energized withthe result that the indication relays LllAi and RGAK are released andthe track indicator lamp iE is dark. In the event an eastbound train isto move through the stretch FI and enters the track section AZT inapproach to signal R4 as well as in the approach to signal Re, theapproach `relay RiiAR is deenergized and released, if signal Rfid isoperated to a proceed position for an eastbound train, closing backcontact 8l and causing an indication code to be transmitted whichresults in the indication relay RSAK being energized. When. the trainpasses signal RAli and enters track section 3T, track relay 'TR isshunted to open the control circuit for approach relay REAR atadditional points and when the east- .bound train enters section 1T toshunt track relay dTR, the circuit for approach relay RcAR is opened atother additional points and the circuit for the approach relay LcAR isopened. Relay LliAR when released to close back contact et causes anindication code to be transmitted from station 3 6 which results inindication relay LAK being energized. Both indication relays LliAK andRiiAK at the oice being now picked up, the lamp 4E is illuminated toiniorm the operator that the section 14T is occupied the eastboundtrain. This condition is continued while the eastbound train traversesthe track sections AIiT and 5T, since track relays AaTR and STR bothcontrol the circuits for both approach relays RbAR and LfiAR. lnmotherWordsthe indication lamp 4E is 4continuously illuminated while theeastbound train occupies the track sections between leaving signals Liand Re.

Assuming that signalRAt is operated to a proceed position to permit thiseastbound train to enter section 5T, the control circuit for approachrelay LliAR is held open at iront contacts i3 and .Sil of track relaySTR While approach relay vREAR is reenergized and picked up when thetrain vacates the section ii' and approach relay REAR on being picked upcauses indication relay RAK to be deenergized with the result that lamp4E becomes dark to indicate that the train has vacated the vstretchbetween the signals Lil and R6. y

In the event it is desirable to Areenergize approach relay LQAR whenthis eastbound train inspection of Fig. 2 when considered in connectionwith the description of the operation of the apparatus for an eastboundtrain.

It is to be seen therefore that I have provided novel and improved meansfor indicating occupancy of a center portion between the two endportions of a stretch of track, .such as, for example, the intermediatetrack section between the two detector track sections of adjacentpassing sidings, or the intermediate track section between the twodetector track sections at the two ends of a passing siding, andrepeater relays for the track sections of such stretches governed arenot required.

'Although I have herein shown and described only two forms of railwaytraii'ic controlling apparatus embodying my invention, it is understoodthat various Vchanges and modications `may be made therein within thescope of the appended claims without departing from the spirit and scopeof my invention.

VHaving thus described my invention, what I claim is:

" 1. In combination, a stretch of single track railway including theadjacent track switches of two' adjacent sidings, said stretch arrangedwith ra detector track section at each of said switches and anintermediate track section between such detector sections, an enteringsignal for each siding located at the junction of the detector sectionof that siding and the intermediate section, a track circuit including atrack relay for `control relays one for each of said signals, a

directional relay for each detector section and Velective when energizedto by-pass the respective approach relay circuit around the track relayof the respective detector section, means governed by each signalcontrol relay when picked up to energize the directional relay for thedetector section at which the associated signal is located, twoindication relays one for each approach relay and each such indicationrelay energized by said remote control system when vtheV respectiveapproach relay is released, and a track .indicator controlled over acircuit including in series a front contact of each of said indicationrelays to indicate when a train occupies said intermediate section only.

-2.` In combination, a stretch of single track railway including twoadjacent sidings and arranged with an intermediate track section be--tween the two detector track sections for the adjacent switches of thesidings, a track circuit including a track relay for each of said tracksections, two entering signals one for each siding, an approach relayfor each such signals, a control circuit for each approach relay andincluding a contact of the track relay for the detector section at theswitch remote from the respective signal and a contact of the trackrelay of the intermediate section, a remote control system associatedwith said stretch and including two signal control relays one for eachof said signals, two. directional relays one associated with each saidsignal control relay and energized over a 4pick-up circuit including afront contact of the vrespective signal control relay and a backcontactof the track relay for the detector section adjacent the signalgoverned by that signal control relay, a by-pass circuit for each of theapproach relay control circuits to by-pass the circuit around the frontcontact of-the respective `detector section track relay and including afront over line circuits requiring additional line wires contact of thedirectional relay for the signal control relay of the signal governingtraffic over that detector section, two indication relays one for eachof said approach relays and each said indication relay energized bysaid' remote control system when the respectiveapproach relay isreleased, and a track indicator controlled over a circuit including inseries a front contact of each of said indication relays.

3. In combination, a stretch of single track formed with two spaceddetector track sections each of which includes a track switch and whichsections are separated by at least one intermediate track section, atrack circuit including a track relay for each of said sections, asignal at each detector circuit to govern traffic over the respectivetrack switch away from said intermediate section, an approach relay foreach of said signals controlled through a circuit including a frontcontact of the track relay of each intermediate section and a frontcontact of the track relay of the detector section remote from therespective signal, a remote control system having an olce from whichsaid signals and switches are governed, means governed by said remotecontrol system to by-pass each approach relay circuit around the frontcontact of the respective detector section track relay according to thecontrol established for the switch and signals associated with thatdetector section, two indication relays at said ofce one for each ofsaid approach relays. means governed by each approach relay to energizethe respective indication relay through said remote control system whenthe respective approach relay'is released,

and a track indicator controlled by a circuit in- `said signals, each ofsaid approach relays controlled by a circuit includingV a front contactof the track relay for said intermediate section and 'a front contact ofthe track relay for the detector section remote from the respectivesignal, a remote control system including a remote office for saidstretchfor governing the switches and signals associated with saidsiding and said system provided with a switch control relay for eachsaid switch, means governed by `each of said switch control relays to attimes by-pass the -approach relay circuit around the front contact ofthedetector track circuit at the respective switch, two indication relaysat said office one foreach of said approach relays, means governed -byeach of said approach relays to energize the 4respective indicationrelay through said remote control system, and an office track indicatorYcontrolled by a circuit including in series a front contact of each ofsaid indication relays.

JAMES J. VANHORN.

